The invention relates to apparatus used to pressurize a removable chromatography cartridge.
In chromatographic procedures, a stationary phase such as a surface active powder is contained in a chromatography column. A mobile phase consisting of a carrier fluid and a sample of chemical to be identified, analyzed, or purified is passed through the column. Different components of the sample pass through the column at different rates and are thereby separated from each other, leaving the column at different times.
Voids in the stationary phase that may have resulted during shipping and other nonuniform packing conditions can deleteriously affect the operation of a chromatography column and the accuracy of the results. It is known to compress flexible-walled columns in order to close voids and provide uniform packing of the stationary phase. E.g., in U.S. Pat. No. 4,250,035, a chromatography column is made of polytetrafluoroethylene (PTFE) tubing sealed at the ends with porous frits. In one embodiment, the column is placed within a chamber that is pressurized to compress the deformable walls of the column and the stationary phase therein. This provides a uniform packing of the stationary phase and promotes the accuracy of the chromatography column.
It is also known to make a chromatography cartridge from polyethylene, or like material, and to mount the cartridge in a pressurizable compression module assembly having an outer cylindrical body and an end cap that has an O-ring around its outer surface for providing a seal with the end of the cartridge. The O-ring is made of resilient, flexible material, so as to provide a good seal, and is chemically-resistant, to reduce interaction with the mobile phase chemicals. Nevertheless, this O-ring may shrink or swell, leach compounds into the column or absorb the sample.